Limestone slab and method of coloring same



Sept. 6, 1938.

F. BLUEM ET AL LIMESTONE SLAB AND METHODDF COLORING SAME Filed Feb. 5, 1937 H WI Patented Sept. 6, i938 UNITED STAT LIMESTONE SLAB METHOD OF COLOB- ING SALE Frederick Bloom and ,Kurt-Blnem, Chicago, Ill.

- Application February 5, 1937, Serial No. 124,178

11 Claims. Our invention relates generally to the coloring and polishing of ordinary limestone, as distin-' guished from the so-called marbles, for the pur I pose of improvingits artistic appearance and enlarging its availability for harmonious decorative treatment. \i j Whilethe color of limestone varies with the amount and character of its oxide content, such as iron oxide, copper oxide, etc., its color value and artistic appeal are considerably below those of the more expensive and decorative stones, such as marble and granite, which, therefore, are particularly adapted for the decorative treatment of interiors. Moreover, the majority of limestones are incapable oi taking a marble-like polish, so

to produce any desired colored effect or design and of further conditioning and treating the stone to produce a high polish on the colored surface.

25 A further object is to provide a polished lime stone slab having portrayed thereon any desired color scheme or design which leaves visible the natural texture of the stone, the slab being thor-- oughly dried and having a protective coating for 30 preventing the subsequent absorption of moisture.

These and further objects of our invention will be set forth in the following specification, reference being had to the accompanying drawing and the novel means by which said objects are eflectu- 35 ated will be definitely pointed out in the claims.

In the drawing: I

Figure 1 is a perspective view of a plain, limestone slab before being treated according to our improved method;

40 Fig. 2 is a plan view of the same slab colored and decorated according to a selected design;

Fig. 3 is an enlarged section along the line H r in Fig. 2, looking in the direction of the arrows and showing the relation of the successive treat- 45 ments to the stone surface. l

' In carrying out our improved method, the lime stone is first cut into slab-like form and preferably to a thickness varying from to 3". At this stage, the surfaces of the slab have the char- 50 acteristic limestone appearance, as represented generically and in greatly exaggerated form by the numeral III in Fig. 3. These relatively thin slabs are employed because of the necessity of preliminarily expelling 'all contained moisture from the slabs which otherwise might later resuit in a peeling or disintegration of the colored surface. 7

Accordingly, the slabs are heated at a temperature of from 120 to 180 F. for a time sumcient to insure the removal of all contained moisture, 5

the time 01'. heating varying with the thickness of the slab. This heating of the slabs is insufficient to effect any disintegration of the limestone and this step of the treatment is characterized by the further advantage of opening the pores of the 10 stone, thus insuring a firm interlock with the slab of the materials thereafter applied.

The next step in'the method consists in applying the, colors to the surface or the dried stone.

These colors may be applied while the stone is 15 cool, or the stone may be slightly warm, but'in any case, it will be understood that, after being dried, the slabs have been so handled as to prevent the reabsorptionof moisture. v

Since one of the important features of our inv vention is the preservation of the natural texture of the limestone, regardless of the nature of the coloring or decorative design applied, weprefer to use our colors in the form of stains, rather than in paint form which would otherwise conceal the stone texture. Further, we prefer to use stains of animal or vegetable origin, and, as vehicles therefor, an easily evaporable liquid, such as alcohol, rather than an oily vehicle which is dimcult to control when applied to a porous stone, such as limestone. These stains may be prepared in any of the well known ways and their strength may be varied as desired to obtain any color intensityand liquidity of stain.

Any of the stains may be applied by a brush, it the design is of the general nature as illustrated in Fig. 2, but it the complete surfaces! the slab is to be colored by a single stain, the latter may be applied by spraying. Owing to the nature of the stains employed and the porosity of the stone,

a slight surface impregnation of the'surtace is efiected, as indicated by the numeral II, and, further, due to the lack of hiding power of the stains, the full texture of the stone surface remains visible after coloring, so that the slab retains its stone appearance; Depending upon the original color and surface characterhtics of the limestone used, it may be necessary to make more than one application of the desired stains to the surface in order to secure the required depth and tone of color.

After the stains have been applied and the surface of the stone is completely dry, we next apply a simple soiution of .alcohol 'and clear white shellac to the colored surface in order to.

fill the deeper portions of the stone pores and also provide an extremely thin, bonding layer 12 Gil with the plastic mass or cement l3'that is next applied. This cement comprises equal partsby volume of powdered limestone, clear white, liquidshellac, and the stain originally used for coloring the stone. 'It will be understood that, if the surface of the slab is originally stained with a single color, then only one similarly colored cement is required but if a decorative design comprising numerous colors is portrayed on the surface, then it is necessary to employ for each colored area a cement that is similarly colored. This cement is characterized generally by the consistency of butter and, due to the presence of the shellac, it is able to form a bonding union with the shellac coating previously applied and so insure the firm holding of the cement in place. This action is facilitated to some extent by the interlocking of the mass with the pores and interstices of the stone surface, the cement acting substantially as a filler in order to facilitate the obtaining of a smooth slab surface that is capable of being polished. This cementitious filler is then permitted to dry which requires from one to three hours. The stone surface is then rubbed down with emery cloth until it is finger smooth and the color and structure of the stone are clearly visible.

Thereafter, the conditioned surface is. rubbed with a clean white, linen cloth thatis dipped in hot olive oil and this oil treatment imparts a slightly glistening appearance to the colored sur face. This appearance is preferably enhanced and the surface protected against normal temperature changes by applying a coat M of a good commercial grade of waterproof varnish. After the varnish is dry, it is rubbed down with a piece of felt dipped first in vinegar and then in powdered hartshorn. This rubbing serves to reduce the thickness of the varnish coat and to remove brush marks and similar light reflecting disturbances on the surface, so that the surface of the slab is not only glass smooth and polished, but retains the original stone texture. If a duller finish is desired, the varnish coat may be omitted.

The foregoing treatment colors and decorates the surface of the slab so treated, and also renders the treated surface resistant to moisture absorption both with and without the varnish coat, since the presence of the shellac in the prefer to coat the untreated surfaces with a solution comprising one and one-half ounces of paraffin which .is melted by boiling in one quart of linseed oil. This solution is applied with a brush to the untreated stone surfaces, such as the edge and back surfaces, and it provides a moisture-proof coating l5. v

By the use of our improved method, therefore, architects and decorators may harmoniously includeordinary limestone in any desired decorative scheme. The application of the method is not restricted in any substantial way, since it is not only possible to color entire stone surfaces with a single color, but also to incorporate thereon'rather complicated designs, such as replicas of the more expensive types of marbles, geometrical and artistic designs of various kinds, and human and animal figures and portraits. One typical arrangement is shown in Fig. 2 which illustrates a vein-like design. Any of these designs may be embodied on a limestone surface without destroying the stone-appearance of the slab which is a. very important advantage, particularly in interior decoration.

We claim:

1. The method of coloring a mnestone slab consisting in thoroughly drying the slab, stain ing the slab surface to be exposed with a selected color, bonding to the stained surface a plastic, cementitious powdered limestone composition having substantially the same color as the original stain, permitting the composition to dry, applying waterproof varnish to the composition treated surface to smooth the same and provide a glistening surface, and then coating the remaining surfaces of the slab with a solution of paraffin to prevent the ingress of moisture.

2..The method of coloring a limestone slab consisting in thoroughly drying the slab, staining the slab surface to be exposed witha selected color, applying clear liquid shellac to the colored surface to fill the deeper pores thereof, covering the shellacked surface with a filler composition comprising limestone dust, white liquid shellac and the stain employed in the original coloring,

comprising limestone dust, white liquid shellac and the stain employed in the original coloring,

permitting the composition to dry, rubbing the surface until finger smooth, applying waterproof varnish to the composition treated surface to further smooth the same and provide a glistening surface, and then coating the remaining surfaces of the slab with a solution of paraffin to prevent moisture absorption.

4. The method of coloring. a limestone slab consisting in thoroughly drying the slab; staining the slab surface to be exposed with a selected color, applying clear liquid shellac to the colored surface to fill the deeper pores thereof, covering the 'shellacked surface with a cementitious filler composition including limestone dust and the stain employed in the original coloring, permitting the composition to dry, rubbing the surface until finger smooth, applying waterproof varnish to the composition treated surface to further smooth the same and provide a glistening surface, rubbing the varnish coat to remove brush marks and provide a substantially polished surface, and then coating the remaining surfaces of the slab with a solution of paraffin to prevent, moisture absorption.

5. A limestone slab having a surface stained with a selected color and bonded thereto a thin filler covering in the form of a composition having substantially the same color as the original stain and including powdered limestone, the covered surface being smooth and having the texture of the original slab.

6. A limestone slab having a surface stained with a selected color and bonded thereto a thin stain and including powdered limestone, the

covered surface being varnished to present a polished appearance and having the texture of 5 andbonded to each colored area a thin filler covering in the form of a composition having substantially the same color as the original stain and includingipowdered limestone, the several coverings bonding at their respective edges with each 10 other to maintain the color integrity and defini- 15 face stained with a selected color and bonded thereto a thin filler covering in the form of a composition having substantially the same color as the original stain and including powdered limestone, the covered surface being smooth and. 50 having the texture of the original slab and the remaining surfaces being coated with paramn to prevent moisture absorption.

9. The method oi coloring a limestone slab consisting in thoroughly dryingthe slab, staining 2 the slab surface to be exposed with a selected color, bonding to the stained surface a plastic, cementitious powdered limestone composition having substantiallythe same color as the original stain, permitting the composition to dry, applying waterproof varnish to the composition treated surface to smooth the same and provide a glistening surface, and then coating the unstained surfaces of the slab with a waterproof coating to prevent the ingress of moisture.

10. The method of coloring a limestone slabconsisting in thoroughly-drying the slab. staining the slab surface to be exposed with a selected color, bonding to the stained surface a plastic, eementitious powdered limestone composition having substantially the same color as the original stain, permitting the composition to dry, and then coating the unstained surfaces of the slab with a waterproof coating to prevent the ingress of moisture.

11. A dry, thin limestone slab having one surface stained with a selected color and bonded thereto a thin filler covering in the form of a FREDERICK BLUM. KURT BLUEM. 

